Asymmetric Fabry-Pérot fiber-optic pressure sensor for liquid-level measurement.

It is demonstrated that an asymmetric Fabry–Perot fiber-optic pressure sensor is capable to precisely measure liquid levels. They are directly proportional to pressures that can modulate cavity length of Fabry–Perot cavity. As a result, the sensor can operate over a linear region of an interference fringe that enables liquid-levels interrogation by measuring the reflected intensity. Experimental results show the resolving power of 0.4 mm, sensitivity of 2.4 mV/mm, and precision of 1 mm over range of 2.3 m (water) can be achieved. The sensor can measure liquid levels accurately, continuously, and automatically in flammable and explosive circumstances.